Compressor



Dec. H6, 3952 K. E. BbL ERuP COMPRESSOR Filed March 14, 1950 INVENTOR 1.4 a M ATTORNEYJ! Patented Dec. 16, 1952 OFFICE,

COMPRESSOR Kay Emil Bollerup, Virum, Kcngens Lyngby, Denmark Application March 14, 1950, Serial No. 149,487 In'Denmark April 1, 1949 3 Claims.

The present invention relates to a compressor, e. g. for use in refrigerating systems and more particularly to a compressor of the type comprising a rotatably mounted cylinder having slidably mounted therein two oppositely reciprocating pistons preferably working on a common compression space. Such compressors have been adopted to a considerable extent, because they are very reliable in operation and produce a minimum of noise, one of the factors contributing towards these desirable properties being the fact that the ordinary valves of such machines may be replaced by a circular slide face for determining the admission and discharge of vapours to and from the rotating cylinder, whereby a very good valve seal is obtained. With a view to this seal and other features of construction, it is of importance that the reaction forces resulting from the piston movement should be taken up symmetrically by the casin enclosin the cylinder, and constructions have therefore been proposed in which each of the pistons is guided in its reciprocating movement by means of stationary guiding curves on both sides of the cylinder. Such guiding curves have, e. g., been used in the form of excentrics, and since the guide curves for the two pistons must have mutually overlappin contours, it has been considered necessary to arrange them in axially offset positions, e. g., in the form of two excentrics mounted side by side in the axial direction.

A structure of this kind comprises a total of four excentrics, via, two on each side of the cylinder, and these excentrics occupy considerable space in the axial direction. Further, the outer excentrics are located at a relative great distance from the centre line of the pistons, so that relatively long transfer members are required between the piston and the excentrics, and finally, it will be difficult to obtain an entirely identical and balanced construction of the two pistons with associated transfer members and excentrics. Moreover, excentrics suffer from the drawback that they offer a positive control of the pistons only in one direction, but on the other hand, if an attempt is made at replacing the excentrics by curved tracks, it is diflicult to avoid interference between the kinematic systems associated with the two pistons, or otherwise such kinematic systems will be mutually different and assume relatively great radial dimensions.

One object of the invention is to construct a compressor of the type referred to in such a manner as to obviate or materially reduce any or all of the drawbacks referred to.

Another object of the invention is to construct a compressor of the type referred to and which is of a simple, symmetric and compact design and is very reliable in operation and at the same time relatively inexpensive to manufacture.

With these and other objects in View, which will appear as the description proceeds, the invention consists in the novel arrangements and combinations of parts which will now be described in detail with reference to one embodiment of the invention and which are set forth in their general aspect in the appended claims.

Reference will now be had to the accompanying drawing in which Fig. 1 shows an axial section through one form of a compressor according to the invention,

Fig. 2 one of the covers of the machine as viewed from the interior of the latter, and

Fig. 3 a sliding shoe belonging to the machine.

In the drawing, l is a cylinder block which is integral with a shaft 1 rotatably mounted in a casing composed of a front cover 5 and a back cover 6 so that by rotating the shaft, the cylinder I may be caused to rotate in the interior of the said casing. 8 is a stuffing box securing an efficient tightness of the passage of the shaft through the front cover 5. The cylinder 1 has slidably mounted therein two pistons 2 working on a common compression space l3. A transverse piston pin 12 is mounted in each of the pistons 2 and carries a curved sliding shoe 3 at each end. The sliding shoes 3 engage in grooves or guiding tracks 4 in the front cover 5 and back cover 6. are located exactly opposite one another and their geometrical location in the front cover 5 is apparent from Fig. 2. From this figure, it will be seen that the front cover 5 has two guiding tracks 4 that are both circular and disposed at opposite excentricities relative to the axis of rotation of the cylinder. Thus, the two tracks will intersect one another as is apparent from Fig. 2. One of the tracks is engaged by a sliding shoe 3 pivoted to one piston, and the other track is engaged by a sliding shoe pivoted to the other piston. It has been found that during the rotation of the cylinder the sliding shoes 3 will remain without difliculty in their respective tracks, and there will be no tendency to jamming or faulty movement at the points of intersection of tne tracks. The shape of the tracks is such that the pistons are caused to reciprocat in oppositev directions in the cylinder, and during this movement the piston pin l2 will move to and fro in longitudinal slots 14 of the cylinder wall.

Fig. 2 also shows one side of the slide or port The guiding tracks of the two covers face 9 formed in the front cover 5. I is an elongated port through which vapours are sucked into the compression space l3 between the pistons through a passage, not shown, in the wall of the cylinder I, said passage extending from an opening in the surface of the cylinder block in contact with the slide or port face 9 substantially on the same radius as the port [0, to an opening in the inner wall of the cylinder substantially in the middle of the compression space l3. A smaller port I l in the slide face 9 controls the discharge of the compression vapours from the compression space l3. It will be understood that the port I0 is in communication through a passage I with the interior of the casing which is constructed in well-known manner to receive the vapours to be compressed, while the port I l is in communication with a discharge pipe, not shown. It is observed, however, that the detailed construction of the means for admitting and discharging vapours or gases to and from the cylinder are not shown in the'drawing since these means do not form part of the invention and may be constructed in conventional manner.

It will be seen from .the above that according to the invention a compressor has been provided in which the guiding curves for the two pistons on each side of the cylinder are situated in one and the same axial plane, and that, as a consequence of this arrangement, the whole construction may be made very compact both axially and radially and will be perfectly symmetric and identical for the two pistons. The compactness of the construction in the radial direction results from the fact that no transfer members are required axially outside the pistons and that also the guiding curves may be kept at a relatively small dimension, which also results in reduced wear, a contingent factor in the possibility of keeping thewhole control system for the pistons down on the smallest possible radial dimensions being the mounting of the sliding shoes associated with each piston on a transverse piston pin slidable in longitudinal slots of the cylinder wall.

Iclaim:

1. A compressor comprising acasing structure,

a drive shaft mounted for rotation in said casing structure, a rotor carried by said drive shaft, said rotor being provided with a cylinder bore extending therethrough at right angles to the axis of said drive shaft, said rotor and said casing structure having co-operating surfaces in which cylinder inlet and outlet ports are provided, a pair of pistons mounted for sliding movement in said cylinder bore at one and the other end thereof respectively, said casing structure being formed with surfaces facing one and the other side respectively of said rotor, each of said surfaces being provided with a pair of grooves, said pairs of grooves on one and the other side of said rotor respectively being exactly similarly located with respect to the axis of said rotor and each pair comprising two intersecting grooves both surrounding said axis and being symmetrically located with respect to a diametrical plane through said axis, and means extending transversely from each of said pistons and engaging similar ones of said grooves on one and the other side of said rotor respectively.

2. A compressor as in claim 1 in which said rotor is constructed at each end of said cylinder bore with a pair of slots disposed diametrically opposite with respect to and extending longitudinally of the axis of said cylinder bore, said means extending transversely from said pistons being in the form of piston pins extending through said slots and carrying curved sliding shoes at their projecting ends for the engagement with said grooves.

3. A compressor as in claim 1 and in which all of said grooves are of circular configuration.

KAY EMIL BOLLERUP.

REFERENCE S CIT ED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 586,669 Shedlock July 20, 1897 682,822 Toepel Sept. 17, 1901 900,988 Domecq-Cazaux Oct. 13, 1908 

